Environmental Biogeochemistry

environmental chemist taking water quality samples

The Environmental Biogeochemistry Section in the Patrick Center is concerned with the influence of organisms on the sources, fate, and transport of chemicals in the aquatic systems. Within the Environmental Biogeochemistry Section many studies deal with the cycling of bioactive elements (carbon, nitrogen, and phosphorus) as well as trace elements (e.g., lead, copper, mercury, and zinc) and organic contaminants such as polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs).

Recent and ongoing studies include the study of nutrient cycling within tidal freshwater wetlands in the Delaware and Anacostia rivers, impact of sea-level rise on C and P cycling in tidal freshwater wetlands, contaminant uptake and food-web dynamics in the Anacostia River, nutrient cycling in tidal wetlands, ponds and riparian zones of free flowing rivers, the effects of stormwater runoff to the water quality of the Anacostia and Potomac rivers, and historical changes in nutrients and contaminants and their impact to the ecology of an estuary.

Staff | Capabilities | Facilities | Selected Projects


Dr. David Velinsky, Director
Dr. Velinsky is a marine biogeochemist with over 20 years experience in marine and freshwater studies related to nutrient cycling, isotope biogeochemistry, and wetland nutrient and metal geochemistry. He started as an organic geochemist studying the transport of organic compounds in estuaries and from atmospheric transport, and shifted to studies of sulfur and selenium geochemistry. He has published studies related to many aspects of biogeochemistry and has a broad range in the cycling of bioactive elements.
Dr. Jeffrey T.F. Ashley, Research Scientist
Dr. Ashley, who is also an Associate Professor in Chemistry at Philadelphia University (faculty.philau.edu/ashleyj/) has expertise in organic contaminant biogeochemistry. Interests include the sources, transport, and fate of bioaccumulative, persistent organic contaminants in natural waters; modeling the bioaccumulation of pollutants in aquatic food webs; the role of eutrophication in determining organic contaminant exposure to organisms; environmental analytical chemistry, assessment of contaminated fisheries.
Support Staff
Mr. Paul Kiry (M.A.; Drexel University) with over 25 yrs experience in all forms of environmental analysis of nutrients and trace metals, Ms. Paula Zelanko (M.S.; Lehigh University) who has background in stable isotope geochemistry and analysis, Mike Schafer (B.S.; Southampton College) who has a background in marine organic chemistry, and Ms. Linda Zaoudeh (B.S.; Temple University) who has a background in geology and organic chemistry.
Recent Interns and REU Students
Ms. Ashley Smyth (B.S; University of North Carolina; 2006) and Ms. Amanda Foskett (B.S. in 2007; Duke University), and Sylvan Klein (B.S. in 2008; Goucher University); Erin McKinley (BS expected in 2010; Northland College)


  • Nutrient cycling in tidal wetlands, rivers and estuaries
  • Stable isotope biogeochemistry of carbon and nitrogen
  • Fate and transport of trace elements in aquatic systems
  • Food chain transfers of organic compounds
  • Mass balance modeling of trace elements and bioactive elements
  • Non-point sources of anthropogenic chemicals in aquatic systems


The Environmental Biogeochemistry Section has a broad range of laboratory and field equipment to conduct a full range of basic and applied studies. Instrumentation includes:

  • stable isotope mass spectrometer
  • nutrient auto-analyzer
  • high temperature combustion carbon and nitrogen analyzer
  • cold vapor Hg analyzer
  • gas chromatographs for chlorinated and non-chlorinated hydrocarbons
  • GC-Electron Capture Detector
  • UV-Vis spectrophotometer
  • fluorometer
  • numerous in-situ water quality meters for pH, dissolved oxygen, salinity/conductivity, and turbidity

Field sampling equipment is generally tailored for the specific project and includes an all plastic Soutar box-corer, Ekman and Ponar sediment grab sampler, Niskin and Van Dorn water bottles, and water pumping systems for trace metal clean methods.

Selected Past and Ongoing Projects

  • Bioaccumulation of Organic Contaminants in the Delaware River Estuary: Role of Tidal Freshwater Marshes. PIs: D.Velinsky and J. Ashley (Philadelphia University); NOAA Sea Grant.
  • Impact of Sea Level Rise on the Cycling of Carbon and Phosphorus in Tidal Freshwater Marshes. Funded by US EPA Star Program. PIs, Dr. Melanie Vile (Villanova Univ.), David Velinsky, and Scott Neubaur (Univ. South Carolina). US EPA STAR
  • Distribution of Sediment Contaminant History in the tidal freshwater Potomac River; Washington, DC. Funded by: District of Columbia, PI: D. Velinsky, G. Riedel (SERC) and J.Ashley; District of Columbia.
  • Historical Changes in Sedimentation and Chemical Loading in Tidal Marshes of the Delaware Estuary. Funded by Delaware River Basin Commission. PI: Chris Sommerfield (UDEL) and D. Velinsky.

Stable Isotope Analysis at the Academy's Members' Night

Each fall, the Academy of Natural Sciences hosts its Annual Members' Night. This popular program provides members with the opportunity to visit the Academy's research and collections facilities and meet with the scientists.

One of the member favorites during this evening is the Fingernail Analysis that conducted by Biogeochemistry Section’s Stable Isotope Lab. Members submit fingernail samples that are analyzed for isotopes of Carbon and Nitrogen. These analyses reveal information about the members’ diet. Read more at www.ansp.org/membership/fingernail.php.